David Devereaux-Weber uses the Sense home energy monitor app to show the spike in electricity use when turning on the coffee maker in his Madison home. The coffee maker uses about 1 kilowatt of electricity, represented by the largest red circle on the tablet. David Devereaux-Weber installed a Sense home-energy monitor to find potential "energy hogs" in his Madison home. An ongoing study by Alliant Energy using the monitors found the average Wisconsin household could save $90 a year by targeting "always on" electronics. Most Wisconsin households could save $90 a year and slash energy use by selectively unplugging devices that draw power even when not in use, according to a study by Alliant Energy.